About RefiCalc

I built this calculator because I watched my parents lose $47,000 feeling good about a refinance.

Spring 2012. They had been in the house since 1998, carrying a 30-year mortgage at around 6.5 percent. Rates had dropped into the low 4s. The guy from Wells Fargo ran the numbers, said they would save $200 a month, and they signed a fresh 30-year loan at 4 percent. Everyone high-fived. The monthly savings were real and immediate. My dad called me that night sounding like he had just picked a winning stock.

Here's what nobody at the closing table mentioned. They had 22 years left on the old mortgage when they refinanced. They signed into a new 30-year. That is eight extra years of interest payments. Even at the lower rate, the term extension outweighed the rate drop. I ran the numbers myself when I was home for Thanksgiving that year. Lifetime interest impact: negative forty-seven thousand dollars. The refi saved them on the month and cost them roughly a year of my mom's teacher salary across the life of the loan.

Neither of them were dumb. Neither was the loan officer. The math just wasn't on the page anyone was looking at. The calculator said "save $200/month". It did not say "but lose $47,000 overall". That's the number that would have changed the decision.

What RefiCalc does differently

Every refinance calculator on the internet shows you the break-even month. That is the month cumulative savings equal the closing costs. Most stop there. We do not. We also show lifetime net impact, which is total interest saved minus closing costs, accounting for the full term of the new loan vs what is left on the old one. Then we turn both numbers into a plain-English verdict: Yes, Maybe, or No.

"Maybe" is the one most calculators refuse to say. Monthly win, lifetime loss. That was my parents' refi. If your calculator cannot tell you when that is happening, it is doing you a disservice.

How the formula was built

Standard amortization. The same closed-form equation every mortgage textbook uses and the same one the CFPB's teaching materials reference. We validated outputs to the dollar against Bankrate's refinance calculator. Break-even month rounding is ceil, not floor, because partial-month closing cost recovery is not a real recovery. Everything is documented in the methodology guide.

Sources we trust for real numbers: the CFPB refinance guide, Fannie Mae research, Freddie Mac's weekly PMMS survey for rate context, and IRS Publication 936 for interest deduction rules. We do not take lender marketing at face value and we do not cite rate-comparison sites as primary sources.

Who this is for

Homeowners doing the math themselves before they sit down with a loan officer. If you have a Loan Estimate in your inbox and three days to make a decision, this is for you. If you are two years out from a potential refi and want to know what a 0.75 percent rate drop would actually save you, this is for you. If you are a mortgage professional who wants to send a client a clean comparison, this is for you.

What this is not

Financial advice. Nothing on this site is. Your situation has variables we do not capture, tax treatment of your specific filing status, state recording fees, lender-specific credits, PMI drop-off timing, cash-flow constraints, other life considerations. Run the numbers here to understand the shape of the decision. Then talk to a licensed mortgage professional and a tax advisor before signing. The full disclaimer is spelled out.

What's next

We're adding cash-out vs HELOC comparison, PMI drop-off modeling, and an amortization schedule export. If there's a scenario the current calculator does not handle, let us know. We're building this one honest number at a time.

About the ads: this site does not run lead-gen widgets or lender affiliate funnels. We will add display ads in the future to fund hosting, and we will always label them clearly. No "compare rates" forms that sell your contact info to loan officers. You came here for math, not a sales call.